Retinoids refer to retinol, retinoic acid or derivatives thereof. The retinoids exhibit various biological functions. In connection with skin, effects on hyperkeratinization and acne have been reported and the efficacy of retinoids such as retinol, retinoic acid, etc. for anti-aging is well known (Dermatologic clinics, 1998, 16, 357-364). Despite the positive effects of retinoids, they are restricted in use because even a small amount can cause skin irritation and they are unstable and easily oxidized and denatured when exposed to the air. Although studies have been conducted to stabilize retinoids, the skin irritation problem or safety problem has not been solved yet.
Researches on aging have been focused mainly on photoaging and intrinsic aging. For photoaging, methods for blocking UV and preventing change caused by UV radiation have been actively studied. Also, methods for alleviating age-related intrinsic aging have been studied. Recently, researches are focused on methods for regulating all the aging phenomena. In particular, studies are being conducted on prevention of aging and extension of life span based on the researches about the genes regulating the aging and life span of individuals.
The above information disclosed in the Background section is only for enhancement of understanding of the background of the invention and it may therefore contain information that does not form the prior art that is already known to a person of ordinary skill in the art.